Ovarian cancer presents at a late clinical stage in more than 80% of patients It is associated with a 5-year survival rate of 35% Thus, there is a great need to develop more promising agents for the treatment and prognosis of ovarian cancer. TGFbeta is known to be a tumor suppressor, and intracellular components that mediate its biological effects can also function in this manner. Further, resistance to the growth inhibitory effects of TGFbeta occurs in approximately 75% of ovarian cancer cases, especially with recurrent disease. We have identified a novel TGFbeta signaling component, termed km23, which is also a light chain of the motor protein dynein. This cytoplasmic component interacts with the TGFbeta receptors and is phosphorylated upon TGFbeta receptor activation. Further, expression of km23 mediates specific TGFbeta responses, including growth inhibition of epithelial cells Moreover, we have identified alterations in km23 in 4 out of 11 epithelial ovarian cancers from human patients, and in 33% of human ovarian cancer cell (HOCC) lines. Since km23 appears to be a TGFbeta signaling component that is altered in human ovarian cancer, we hypothesize that expression of the "tumor-like" km23 alterations in TGFbeta-sensitive HOCCs will suppress the ability of TGFbeta to inhibit the growth of these cells, and produce a more malignant phenotype The overall goal of this proposal is to determine whether the km23 alterations identified in ovarian cancer patients will result in altered growth control by TGFbeta, a more transformed phenotype in vitro, and increased tumorigenicities in vivo. We will also extend our analyses of human cancer tissues to determine the frequency and stage of disease at which the changes occur, as well as the frequency in the normal population. Additional studies will identify the kinase that phosphorylates km23, as well as the precise km23 phosphorylation sites. Finally, we will identify the exact domains of interaction between km23 and the intermediate chain of the motor protein dynein, and determine how alterations in km23 affect this interaction. We hypothesize that the latter two types of studies will assist in the development of screens by which to identify novel agents for the treatment of ovarian cancer [unreadable] [unreadable] [unreadable]